Various types of terminals equipped with display devices having touch panels are known. For example, Patent Documents 1-3 describe display devices that can be operated not just by one of the user's fingers but by the touch of two or more fingers (multi-touch).
Patent Document 1 describes a touch panel system that enlarges or reduces (scales) display information on a screen such as still images or Web pages or the like through the operation of moving two fingers apart or closer together.
Patent Document 2 describes a system in which a map displayed on a panel screen of a display device can be enlarged or shrunk by an operation with two fingers and in addition cabin temperature can be adjusted on a car air conditioner through an operation by three fingers.
Patent Document 3 describes a display device in which two display units equipped with touch panels are positioned adjacent to each other, wherein the display device calculates the movement distances of the positions of a first finger on the first touch panel and a second finger on the second touch panel, and if there is a difference of at least a defined value in the movement distances, enlarges or reduces image data displayed on the display unit in accordance with the change in distances.